1. Field of the Invention
The present invention relates to an image forming apparatus for recording an image corresponding to an original image on a recording medium.
2. Description of the Related Art
An automatic original feeder is arranged in an image forming apparatus such as an electronic copying apparatus to automatically feed an original to an original table or to feed it from the original table. An opening portion is formed in, e.g., an original table cover in the automatic original feeder. A carrying roller for carrying an original is arranged on the table in the location corresponding to the opening portion. When an original is to be copied by an electronic copying apparatus having the automatic original feeder, an original fed to the original table in the automatic original feeder is exposed and scanned by an exposure/scanning unit while the original is kept in contact with the original table by means of the original table cover.
When a thin original is to be copied by the electronic copying apparatus having the automatic original feeder, light emitted from the exposure/scanning unit is reflected by the original and is also transmitted through it and reflected by the original table cover. These light components reflected by the original and the original table cover are radiated on a photosensitive drum through an optical system. Since a contact surface of the original table cover is white or has a light color, a portion in contact with the original table cover is copied to accurately reproduce an original image because an electric charge of the corresponding portion of the photosensitive drum is removed by the light reflected by the original table cover.
A portion corresponding to the opening portion of the original table cover has a small amount of reflected light because light emitted from the exposure/scanning unit and transmitted through the original is attenuated, and the electric charge of the photosensitive drum is not sufficiently removed. Therefore, an unwanted image, corresponding to the opening portion of the original cover is formed in the copied image, thus posing a serious problem.